Mounting structure for flangeless fuel tank

ABSTRACT

An improved mounting structure for a flangeless fuel tank forcibly maintains an air-tightness at joined parts between top and bottom halves of a tank when the fuel tank is welded, thereby reducing the space and weight of the tank. The fuel tank is increased in capacity as much as a space of a flange can be adopted. The mounting structure comprises a top half of a tank protrusively formed at a lower external lateral surface thereof with a plurality of studs, a bottom half of a tank formed with grooves corresponding to the plurality of studs and partially inserted into the lower distal end of the top half of the tank, and fastening members for being fastened to the studs of the top half of the tank so that the top and bottom halves of the tank can be air-tightly welded.

FIELD OF THE INVENTION

The present invention relates to a mounting structure for a flangelessfuel tank and, more particularly, to a mounting structure in which thetop half of the tank can be securely and simply assembled with thebottom half of the tank via welding without flanges.

BACKGROUND OF THE INVENTION

In general, vehicles are equipped with metal fuel tanks for storing acertain amount of fuel and continuously supplying fuel to be consumed inengines. A prior art discloses a fuel tank manufactured by joining twohalves of a tank along mating circumferential flanges formed in eachhalves via lap welding.

Another frequently used prior art discloses a fuel tank manufactured byjoining top and bottom halves of a tank via seam welding. Generally, aseam welding is a type of electric resistance welding primarily used forseam welding a metal plate, where welding parts of the metal plateoverlap and are inserted into a pair of rollers comprising electrodesare inserted, allowing the overlapped welding parts to be welded byrotation of the rollers. The electrode rollers feed the plates and actas seam electrodes at the same time.

The seam welding using a seam welder is usually applied to a seam partto obtain an air-tight sealing such that it is advantageous for the seamwelding to be used for welding top and bottom half plates of a tank.However, there is a drawback in that abrasion occurs easily due tofriction generated between the seam electrodes and the plates resultingin a frequent change of electrodes, thereby increasing manufacturingcosts.

There is another drawback in that the welding quality deteriorates whencontact surfaces of the plates are uneven and the welding zone betweenthe electrodes and plates is broad compared to other welding methods,resulting in a greater thermal deformation, which in turn gives rise tocracks in response to fluctuation of fuel or impact.

As a result, many prior arts disclose a fuel tank manufactured bywelding a top plate to a bottom plate of a fuel tank via welding methodsother than the seam welding method. For example, U.S. Pat. No. 5,626,776entitled “Flangeless Fuel Tank” has been disclosed. As illustrated inFIGS. 7 and 8, a flangeless fuel tank (10) is comprised of a lowerfemale half (14) and an upper male half (12). Circumferential walls (16,18) of the female and male halves (12, 14) are interfitted andoverlapped areas thereof are welded and integrated. Furthermore, thefemale and male halves (12, 14) are formed at the overlapped areasthereof with protrusions (20, 22) and a plurality of dimples (30) areformed to fix positions prior to the welding. A laser beam weldingapparatus welds the clamped tank halves (12, 14) along the alignedwelding lines to create a continuous welding.

However, there is a disadvantage in the flangeless fuel tank weldingmethod thus described according to the prior art in that, although thereis an advantage in that the capacity of the tank can be increased asmuch as the width of the flange and the weight of the tank can bereduced, the protrusions (20, 22) and dimples (30) should be formed atthe laser-welding parts of the tank halves (12, 14) in order to improveairtightness and fixing positions during welding.

There is another disadvantage in that it is structurally difficult tohave accurate positions and overlapped portions of the welding partswhich greatly influence the quality of the welding, and it is difficultto maintain gaps between overlapping portions of the two halves of atank around their entire circumferential areas at a constant level.

SUMMARY OF THE INVENTION

The present invention is disclosed to solve the aforementioned problemsand it is an object of the present invention to provide a mountingstructure for a flangeless fuel tank adapted to easily weld top andbottom halves of a tank in a simplified manner and to limit insertionlengths of welding parts.

In accordance with a preferred embodiment of the present invention,there is provided a mounting structure for a flangeless fuel tank inwhich a lower circumferential end of a top half of a tank is inserted atone part thereof to an inner upper circumferential surface of a bottomhalf of a tank, and an overlapped portion therebetween is integrallywelded, wherein a plurality of studs, each spaced out therebetween, areprotrusively formed at an external lower end surface of the top half ofthe tank. A plurality of grooves are formed at the upper end of thebottom half of the tank to accommodate the plurality of studs, and aplurality of fastening members are used for being fastened to a distalend of each stud and for fastening the joined part between the top andbottom halves of the tank.

In accordance with a second preferred embodiment of the presentinvention, there is provided a mounting structure for a flangeless fueltank in which protrusive stoppers are further formed at the innersurface of the bottom half of the tank and each protrusive stopper isdistanced from the upper end of the bottom half of the tank.

In accordance with a third preferred embodiment of the presentinvention, there is provided a mounting structure for a flangeless fueltank in which the fastening member is formed with a hollow hole formedwith female threads corresponding to male threads formed at acircumferential surface of a stud, and an external end of the hollowhole is further formed with a flange for contacting the external surfaceof the bottom half of the tank.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the presentinvention, reference should be made to the following detaileddescription with the accompanying drawings, in which:

FIG. 1 is a perspective view of a welded structure of an automobile fueltank according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a an enlarged cross-sectional view of a welded part accordingto an embodiment of the present invention;

FIG. 4 is an enlarged and exploded perspective view of principal partsof the present invention;

FIG. 5 is a cross-sectional view of a welded state of FIG. 4;

FIG. 6 is a constitutional view for illustrating a fastening memberaccording to another preferred embodiment of the present invention;

FIG. 7 is an exploded perspective view of an exemplary conventionalflangeless fuel tank; and

FIG. 8 is a cross-sectional view of a welded principal part shown inFIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be describedin detail with reference to the annexed drawings, where the presentembodiments are not limiting the scope of the present invention but aregiven only as an illustrative purpose.

As illustrated in FIGS. 1-5, a mounting structure for a flangeless fueltank includes a top half of a tank (110) protrusively formed with aplurality of studs (115) at the lower external surface of the top halfof the tank, and a bottom half of a tank (120) for being partiallyinserted into the lower end of the top half of the tank (110). Thebottom half of the tank is formed with a plurality of inversely-archedgrooves to correspond with the plurality of the studs (115), and aplurality of fastening members (210) are used for being fastened to eachstud (115) to couple the top and bottom halves of the tank (110, 120).

Preferably, stoppers (122) are protrusively formed at the inner uppersurface of the bottom half of the tank (120) to allow the top half ofthe tank (110) to be accommodated at a lower end thereof. To be morespecific, each stud (115) is shaped of a pin or a bolt and is formed atthe external side of the top half of the tank (110). Each stud is formedwith male threads. In the first embodiment of the present invention, anut is exemplified for the fastening member (210) with a hollow hole(212).

Preferably, the hollow hole (212) is formed at an inner circumferentialside thereof with female threads for being screwed to the studs (115)and the nut is formed with a flange (215) for contacting the externalsurface of the bottom half of the tank (120).

Preferably, each stopper (122) protrudes toward the interior of thebottom half of the tank (120), each stopper (122) being arrangedoppositely from each other at the inner circumference of the bottom halfof the tank (120). Preferably, the stopper (122) can partially be formedin a ring-shape at the inner circumference of the bottom half of thetank (120).

The operation of the present invention will now be described in detailwith the accompanying drawings.

First, the assembly process will be explained. When a lower distal endof the top half of the tank (110) is partially inserted into theinterior of the bottom half of the tank (120), the lower distal end ofthe top half of the tank (110) is accommodated by the interference ofthe stopper (122) of the bottom half of the tank (120) and the stud(115) of the top half of the tank (110) is fitted into the groove (125)of the bottom half of the tank (120).

Successively, when the distal end of the externally-protruded stud (115)is assembled with the fastening member (210) and rotated, threads formedat the hollow hole (212) of the fastening member (210) and threadsformed at the external circumference of the stud (115) are mutuallyassembled, and the flange (215) of the fastening member (210) contactsthe external side of the bottom half of the tank (120).

The joined parts between the bottom half of the tank (120) and the tophalf of the tank (110) are mutually and tightly abutted by a screwingforce from the fastening member (210) and the stud (115). At this time,the screwing force from the fastening member (210) is transmitted to thestud (115) while the flange (215) of the fastening member (210) issupported onto the external side of the bottom half of the tank (120),thereby creating a force of pulling the top half of the tank (110)outward. In other words, a gap at the joined parts between the bottomhalf of the tank (120) and the top half of the tank (110) can beadjusted by the fastening force between the stud (115) and the fasteningmember (210), and the gap can be appropriately maintained for welding ofthe joined parts.

Successively, the joined parts between the top and bottom halves of thetank (110, 120) are integrally assembled via welding in which anair-tight and water-tight fuel tank without a flange can bemanufactured.

For reference, the joined part between the top and bottom halves of thetank (110, 120) is approximately within 0.2 mm in case of laser welding,plasma welding and soft brazing, and in case of carbon dioxide welding,the gap within approximately 0.5 mm must be maintained.

Meanwhile, FIG. 6 shows a second embodiment of the present invention inwhich a nut runner (300) is adopted instead of a nut as a fasteningmember of the first embodiment. A mounting structure for a flangelessfuel tank according to the second embodiment of the present inventionincludes a runner body (310) horizontally operable on a verticallymovable jig (400) to allow accommodation with the top half of the tank(110) and a bottom half of the tank (120), a fastening member (320)rotatably mounted on the upper side of the runner body (310) forfastening a stud (115), and a support (330) mounted at a position closeto the fastening member (320) for supporting one side of the bottom halfof the tank (120).

In the structure equipped with nut runner thus described, the top andbottom halves of the tank (110, 120) provisionally assembled with thejig (400) are lifted to rotate the fastening member (320) and to befastened to the stud (115), and the support (330) abuts on one lateralsurface of the bottom half of the tank (120). Successively, the jig(400) is retracted to pull the top half of the tank (110) to allowmaintaining an air-tightness with the bottom half of the tank (120). Thecircumference at the joined parts is assembled via welding while theair-tightness is maintained between the top and bottom halves of thetank (110, 120).

Successively, when the welding is finished, the jig (400) is detached tocomplete the airtight fuel tank.

Although the present embodiment has described an air-tight structurewhere the top and bottom halves of a tank (110, 120) are fastened bystuds (115), it is not intended to limit the invention to the preciseform disclosed, and modifications and variations are possible in lightof the above teachings or may be acquired from practice of theinvention. It is intended that the scope of the invention be defined bythe claims appended hereto, and their equivalents.

As apparent from the foregoing, the present invention is an improvementof a mounting structure for a flangeless fuel tank by forciblymaintaining an air-tightness at joined parts between top and bottomhalves of a tank when the flangeless fuel tank is welded. There is anadvantage in the mounting structure for a flangeless fuel tank thusdescribed according to the embodiments of the present invention in thatspace and weight can be reduced, and a fuel tank increased in capacityas much as a space of a flange can be adopted.

1. A mounting structure for a flangeless fuel tank in which a lowercircumferential end of a top half of a tank (110) is partially insertedto an inner upper circumferential surface of a bottom half of a tank(120) and an overlapped portion therebetween is integrally welded,wherein a plurality of studs (115), each spaced out therebetween, areprotrusively formed at the external lower end surface of said top halfof the tank (110), and a plurality of grooves (125) are formed at theupper end of said bottom half of the tank (120) to accommodate theplurality of said studs (115), and a plurality of fastening members(210) are used for being fastened to a distal end of each said stud(115) and for fastening a joined part between said top half of the tankand said bottom half of the tank (110, 120).
 2. The mounting structureaccording to claim 1, further comprising protrusive stoppers (122)formed at the inner surface of said bottom half of the tank (120), eachsaid protrusive stopper distanced from the upper end of said bottom halfof the tank (110).
 3. The mounting structure according to claim 1,wherein each said fastening member (210) is formed with a hollow hole(212) formed with female threads corresponding to male threads formed ata circumferential surface of said stud (115), and the external end ofsaid hollow hole (212) is further formed with a flange (215) forcontacting the external surface of said bottom half of the tank (120).